Kaposi's sarcoma-associated herpesvirus (KSHV) is a new human herpesvirus (HHV8) believed to cause Kaposi's sarcoma (KS) 1,2!.
Kaposi's sarcoma is the most common neoplasm occurring in persons with acquired immunodeficiency syndrome (AIDS). Approximately 15-20% of AIDS patients develop this neoplasm which rarely occurs in immunocompetent individuals. Epidemiologic evidence suggests that AIDS-associated KS (AIDS-KS) has an infectious etiology. Gay and bisexual AIDS patients are approximately twenty times more likely than hemophiliac AIDS patients to develop KS, and KS may be associated with specific sexual practices among gay men with AIDS. KS is uncommon among adult AIDS patients infected through heterosexual or parenteral HIV transmission, or among pediatric AIDS patients infected through vertical HIV transmission. Agents previously suspected of causing KS include cytomegalovirus, hepatitis B virus, human papillomavirus, Epstein-Barr virus (EBV), human herpesvirus 6, human immunodeficiency virus (HIV), and Mycoplasma penetrans. Non-infectious environmental agents, such as nitrite inhalants, also have been proposed to play a role in KS tumorigenesis. Extensive investigations, however, have not demonstrated an etiologic association between any of these agents and AIDS-KS.
Immediate early protein (IEP) is the product of one of the immediate early genes of herpesviruses. In herpes simplex infection, immediate early genes are defined by their transcription after infection in the presence of complete inhibition of protein synthesis (Virology, Bernard N. Fields, ed., 1996, Lippincott-Raven, Philadelphia). Immediate early genes ensure efficient transcription of the viral DNA genome immediately upon entry into the cell. Infection with many viruses leads to an inhibition of transcription of cellular protein-coding genes by host RNA polymerase II. For DNA viruses, inhibition of host transcription might allow the host-cell RNA polymerase II to transcribe the viral genome in addition to decreasing competition for triphosphate precursors and transcription factors (Virology, Bernard N. Fields, ed., 1996, Lippincott-Raven, Philadelphia).